I'm in the process of changing from an ISP settop box solution to a 'cheaper' ISP with IPTV. The IPTV is still expensive, but I live with my elderly mother, so I need reliability and simplicity.
The first problem is having to use two remotes, so I was considering getting a cheap universal remote to power off the TV when the Android box goes off. I assume someone makes an Android universal remote? It might be easier to leave the TV on, as it will go into power saving mode anyway.
Problem #2 is getting the Android box to default to the IPTV app when it powers on and lock out everything else.
If your media box supports HDMI-CEC, or whatever it might be called, your TV may already turn on or off as your box is powered.